Electrical heating device



June 2, 1953 Q H, HAYNES 2,640,906

I ELECTRICAL HEATING DEVICE K Filed June 2, 1949 .SW1-ver SW'VrCJ-L Patented June 2, 1953 UNITED STATES PATENT OFFICE ELECTRICAL HEATING DEVICE Clyde H. Haynes, Elyria, Ohio Application June 2, 1949, Serial No. 96,779

(Cl. 21g-37) 4 Claims.

My invention relates to electrical heating elements having conductive and non-conductive films sandwiched together, and especially the heating of localized areas of a surface member by a plurality of these electrical heating elements.

One of the most common uses of my invention is in the manufacture of household cooking I have discovered an electrical heating element which may be mounted on the under surface of the stove top. With these electrical heat.. ing elements engaging a localized area of the stove top, I have found that the whole surface of the stove top may be constructed perfectly level and smooth. The stove may be cleaned very quickly and easily since the top is a smooth and waterproof surface.

Therefore, one of the objects of my invention is to provide an electrical heating unit having a surface of predetermined area with at least one sandwich heating element engaging an area less than the predetermined area of the electrical heating unit.

Another object of my invention is to` provide a surface member having ya surface of predetermined area with means for heating a plurality of localized areas which are less then, and merge with the predetermined surface area.

Another object ofmy invention is to provide an electrical sandwich element comprising a plurality of non-conductive and conductive films sandwiched together.

Still another object is to provide an electrical heating element having non-conductive films and conductive resistance films sandwiched together and adapted to be connected in various electrical circuit connections.

Other objects and a fuller understanding of my invention may be had by referring to the following description and claims, ltaken in conjunction with the accompanying drawings, in which:

Figure l is a cross-sectional view of an electrical heating unit illustrating the use of my sandwich heating elements.

Figure 2 is a cross-sectional view illustrating a modification of my electrical heating unit; and

Figure 3 represents the top surface of an electrical heating unit with the localized heated surface areas being representedby dotted lines.

My electrical sandwich heating element as is illustrated in Figure 1 comprises non-conductive .films I 0, II, and I2 sandwiched together with conductive films I3 and I4. In this Figure 1, I illustrate the non-conductive films I0 and Il as being constructed from a form of glass, and the non-conductive film I2 from a heat insulating material. The non-conductive films may be of any suitable material which will withstand the heat generated by the conducted films, and which will electrically insulate one film from the other film. When the non-conductive film I0 is used as the top of the cooking stove, and is constructed from glass, the sandwich element becomes visible relative to the stove top surface so that the localized heat area may be readily located. The conductive films I3 and I4 may be constructed of any resistance material which will conduct electricity. The film may be a coating or a lamination material which is relatively thin whereby the films may be sandwiched together.

The conductive film I3 is electrically connected to an electrical switching mechanism by means of terminals I5. rIhese terminals I5 electrically engage the conductive film I3 at spaced points of engagement and extend outwardly from the sandwich unit thus providing electrical connection terminals for the film I3. Similarly, terminals I6 engage the conductive film I4 and provide electrical connection terminals for this lm. It is understood that any suitable switching mechanism may be used which will control the circuit connection of the conductive films '13, and I4 to a source of electricity 22. The switching mechanism illustrated symbolically in Figure 1 may be any conventional switch which permits the energization of either conductive film individually, the energization of the conductive films in series, and also the energization of the conductive films in parallel circuit.

In Figure 1, I illustrate a plurality of sandwich heating units such as the heating units II, and I8 mounted on a common member herein illustrated as the non-conductive film I0. The non-conductive film or member I0 may be an electrical stove top having a surface I3 of predetermined area. In Figure 3, I best illustrate by means of dotted lines that the area of the stove top I0 engaged by the sandwich heating element Il or the sandwich heating element I8 is less than the predetermined area of the surface I9. When the heating element I'I is energized, a localized area substantially bounded by the dotted line 20 of Figure 3, of the surface I3 will be heated. Similarly when the sandwich heating element I8 is energized a localized area bounded by the dotted line of the surface IS will be heated. I have thus provided an electrical heating unit wherein a plurality of conductive and non-conductive films are sandwiched together and engage, and thereby heat a localized area of ya surface member having a predetermined area greater than the localized area.

In Figure 2, of my drawings I illustrate another form of my invention. In this instance a surface member l23, engaged by a plurality of heating elements including the heating elements 24, and 25. The heating elements 24, and each heat a localized area of the total surface area of the surface member 23. The surface member 23 may be metal ,as illustrated in the drawing, or any other material which has a continuous smooth surface. The heating element 24 is constructed by applying a film or coating of non-conductive material 25 onto localized area of the surface member 23.

Next a conductive material may be coated on `this non-conductive material 2E `rwith the .non conductive material -26 insulating the :conductive inateriai `from 'the surface lmember 23. The sandwich heating element 24 is completed by applying another coating of non-conductive ma- -terial 26, and then acoating of conductive material -2-9. The heating element 225, lis constructed similarly with like members representing like parts -of the heating element '24.

Terminals '3Q provide electrical connection means by connecting lthe conductive material 27 -to a source of energy, and terminals 3l provide means for-connectingthe conductive material 29 to a source of energy. The heating elements comprising the Aconductive and non-conductive materials sandwiched together may then-be covered by glass 32, or any-other waterproof insulation material which `will withstand heat generated bythe heating elements.

Although the invention has been described in L' 'its preferred form with a certain degree of particularity,it is understood Vthat the lpresent disclosure of 'the preferred Aform has'beenmade only by way of example and that numerous changes in the 'details of construction `and vthe combination and arrangement of parts may be resorted to without departing from the spirit and the scope of the invention as hereinafter claimed.

kWhat is claimed 'isz Il. .An electric stove top providing a plurality of individual localized heat areas 'for cooking, said stove top comprising, .asing'le supporting member of electrically non-conductive heat insulating and heat resistant material ,having a top surface, said single supportingmexnber having a plurality of recesses therein opening on said top surface and defining Alocalized heat areas with .the recesses spaced fromeachother and providing a plurality of individual bottom surfaces, a first individual'electrically conductive heat producing coating adherently applied .only to each individual bot cin surface, a first electrically non-conductive coating adherently applied .only to each of .said first electrically conductive heat producing coatings within each recess, a second individual electrically conductive heat producing coating adherently appliedonly to each of said electrically non-conductive coatings within each of said spaced recesses, said first and second conductive heat producing coatings and said first non-conductive coating in each recess having a. combined thickness generally equal tothe distance between said bottom surface and said top surface thereby'positioning said second ,heat producing Vcoating in the general plane of said top surface, and a thin coating having physical properties tending lto prevent transmittal of "heat from said localized heat area to the remainder of the thin coating, said thin coating of smooth water-proof heat resistant Amaterial electrically non-conductively and adherently applied to all of the second individual conductive coatings in said spaced recesses and also adherently applied to all of the top surface of .the `member between the spaced recesses and thereby forming therewith a smooth water-proof surface top for an electric stove.

2. An electric stove top providing a plurality of individual localized heat areas for cooking, said Vstove-top comprising, a single supporting member of electrically non-conductive heat insulating and heat resistant material having a top surface,

said single supporting member having a plurality of recesses therein opening on said top surface and defining localized Vheat areas with the recesses spaced from each-other and providing a lplurality `of individual 'bottom surfaces, a first individual electrically conductive heat producing coating adherentlyapplied only to each individual bottom surface, a first electricallynon-conductive coating adherently applied'only to each 4 of said rst el cfricaliy conductive heat produc- 'ingcoatingswithin each recess, a second individual Velectrically conductive lieatproducing coatin g vadherently applied only -to each of said electrically non-conductive coatings within each of said Ispaced recesses, said first and second conductive Aheat producing coatings and said first non-conductive coating 'in each recess vhaving a combined thickness generally equal tothe distance between said bottom surface and said top surface thereby positioning said second heat producing coating in the kgeneral plane of said top surface, and a single smooth `water-proof coating of electrically non-conductive `heat insulating 'and heat resistant material adherently applied to all of the second Aindividual conductive coatings in said 'spaced recesses vand also ,adherently applied /to all of the `top surfaceof the member between the spaced recesses -and thereby forming therewith a smooth water-proof surface top vfor Aan electric stove.

3. An electric stove vtop as set forth and defined in claim 2 wherein the area of ,the first electrically conductive heatproducing coating is different than the area of the second electrically conductive heat producing coating.

4. An electric stove top as set forth and defined in claim l wherein the'thincoating contains metallic material.

.CLYDE H. HAYNES.

yReferences Cited Ain the nie of this patent UNITED .STATES .PATENTS Number lName Date 617,375 Voigtet al.V Jan. 10, 1899 1,476,116 Thompson Dec. 4, 1923 1,672,724 McCormick .June 5,1928 1,711,472 Lewin Apr. 30, 1929 2,119,680 Long June 7,1938 k2,179,924 Jones Nov. 14, 1939 2,276,005 Vouvalidis Mar. yl0, 1942 2,321,587 Davie et al June l5, -1943 2,367,626 `Shroyer `etai Jan. 16, 1945 .2,409,244 Bilan Oct. 15, 1946 2,416,645 Rutenber lFeb.25, 1947 V,2,429,420 McMaster -Oct. 2l, 1947 2,495,788 'Irist Jan. l, 1950 :FOREIGN PATENTS Number Country 'Date 461,275 Great `Britain Feb. l5, 1937 666,694 .Great Britain Aug. 23,1948 

